The present invention relates to a static eliminator and an electric discharge module for eliminating static electricity from an object to be processed such as an electronic component charged with static electricity.
In the case of manufacturing and assembling the electronic components, if static electricity is charged in jigs etc. for manufacturing and assembling the electronic components, foreign substances such as dust adhere to the electronic components etc. and defective goods are produced, whereby the electronic components during a transfer process are mutually attracted and contact with each other and cannot be transferred smoothly. Therefore, a static eliminator also called an ionizer or ion generator is used to blow ionized air onto the object to be processed such as a portion or component charged with static electricity. In order to ionize air through electric energy, a high voltage is applied to a needle-shaped discharge electrode to generate a non-uniform electric field around the discharge electrodes, whereby a corona discharge is caused in the non-uniform electric field and the surrounding air is ionized by the corona discharge. When a high plus voltage is applied to the discharge electrode, the discharge electrodes absorb electrons from air near the electrodes and the air becomes positive ions. When a high minus voltage is applied, the discharge electrodes discharge electrons and then the air becomes negative ions.
When a high alternating-current voltage is applied to the discharge electrode, positive and negative air ions are generated basically to the same amount. When such ionized air is blown onto an electrified object to be processed (hereinafter abbreviated as “object”), the object repels the same polarity ions and attracts opposite polarity ions thereto. For this reason, when the opposite polarity ions contact with the object, an electric charge level of the object decrease gradually. Consequently, the object becomes in an equilibrium state at a low potential and is neutralized.
Such a static eliminator includes one as disclosed in Japanese Patent Laid-Open Publication No. 2004-253192, i.e., one called a fan type in which air blown by a fan onto the object is ionized by the discharge electrode.
When air is ionized by the corona discharge, insulating materials such as foreign substances educed out from the air adhere to a tip of the discharge electrode and are therefore required to be removed regularly. Furthermore, when the tip of the discharge electrode is worn down or deteriorates, replacement of the discharge electrode is necessary. For this reason, the static eliminator disclosed in the above gazette is constituted by: a frame-shaped detachable unit in which a circular hole, to which a plurality of discharge electrodes are attached opposite to one another, is formed and to which a high-voltage power-supply unit is attached; and a main body case in which a fan is incorporated and to which the detachable unit is attached. Thereby, when any discharge electrode is worn down, the detachable unit is replaced. The discharge electrodes are attached to the detachable unit so as to mutually oppose, toward a center portion of the circular hole, an inner circumferential face of the circular hole in which air flows. Therefore, an inner diameter of the circular hole must be enlarged to ensure sufficiently a ionized air flow rate and enlargement of the detachable unit is required accordingly. Since the detachable unit is made large, the high-voltage power-supply unit can be mounted on the detachable unit.